Distinct alterations in the distribution of CD45RO+ T-cell subsets in HIV-2 compared with HIV-1 infection

Some clinical studies indicate that disease progression in HIV-2-infected subjects may be slower than in HIV-1. We investigated whether there were differences in the distribution of CD45RO+ (memory) and CD45RA+ (naive) T-cell subsets between HIV-1 and HIV-2 infection. Analysis of lymphocyte subsets was performed by flow cytometry in peripheral blood mononuclear cells from healthy controls, HIV-1-(n = 49) and HIV-2-infected (n = 47) individuals divided into two groups: asymptomatic (ASY)/persistent generalized lymphadenopathy (PGL) and AIDS-related complex (ARC)/AIDS. Both HIV-1- and HIV-2-infected patients had significant reductions in the absolute number and percentage of CD4+ lymphocytes compared with seronegative individuals. No significant differences were found between HIV-2- and HIV-1-infected subjects in the same clinical stage. CD4+CD45RA+ cells were significantly reduced in HIV-1 and HIV-2 ARC/AIDS patients and mildly reduced in ASY/PGL HIV-1 and HIV-2 patients. There were no differences in the degree of reduction of CD4+CD45RO+ cells in ASY/PGL HIV-1 versus HIV-2 patients. However, in HIV-1-infected ARC/AIDS individuals the reduction in the percentage of this subset was more pronounced than in HIV-2 infection and this difference reached statistical significance. The increase in CD8+ lymphocytes (percentage and absolute number) was more pronounced in HIV-1 and the differences between HIV-1- and HIV-2-infected patients were statistically significant. CD8+CD45RO+ cells were significantly increased both in ASY/PGL and ARC/AIDS HIV-1-infected patients, whereas HIV-2-infected ASY/PGL patients had normal levels of these cells and HIV-2-infected ARC/AIDS patients had increases that were much less pronounced than that observed in HIV-1-infected ARC/AIDS patients. Significant differences in the absolute number and percentage of this subset between HIV-1- and HIV-2-infected individuals in similar clinical stages were found. HIV-2-infected individuals exhibit a lesser degree of depletion of memory CD4+ cells and a more limited expansion of CD8+CD45RO+ subset, which could be related to the putative lower immunopathogenicity of HIV-2.